Container

ABSTRACT

The bottle-shaped container is made in a coextrusion blow molding process and has a dimensionally stable outer container and an easily deformable inner bag which consist of different thermoplastic materials that cannot be welded to each other. The preform has a diameter greater than that of the bottle neck so that, when the blow mold is closed, the blow mold halves squeeze off excess material not only on the bottom, but also in the shoulder and neck area. Unwelded seams of the outer container are thereby formed in the shoulder and neck area. In the bottom area the outer container is closed by a weld seam which has been formed by displacing material, the weld seam of the inner bag being fixed in said area. After negative pressure has been applied to the inner bag, holes are formed in the upper area of the outer container for the purpose of a permanent pressure compensation. All openings in the outer container are covered by the pump housing. The container operates reliably in the upside-down position.

BACKGROUND OF THE INVENTION

This invention relates to a container, in particular a bottle-shapedcontainer, consisting of a substantially dimensionally stable outercontainer or inner bag which are made in a coextrusion blow moldingprocess from different thermoplastic materials that do not combine witheach other, the container having an upper shoulder section whichpreferably passes into a container neck to which a pump is attached fordischarging the filling of the inner bag.

Such a container is e.g. used for the reception and dosed discharge ofmedicinal liquids. The negative pressure which is required for emptyingthe inner bag can be produced by manually operating the pump which isprovided with a valve.

To enable the per se easily deformable inner bag to contract upon theapplication of a negative pressure for the dosed discharge of a liquid,it is necessary for a container of the type in question that air canflow into the space between the dimensionally stable outer container andthe easily deformable inner bag, so that no negative pressure is createdthere by the reduced volume of the inner bag, Such a negative pressurewould impair the further emptying operation and make such an operationimpossible in the end.

SUMMARY OF THE INVENTION

It is the object of the present invention to develop a container of thetype in question in such a way that the above-mentioned disadvantagesare eliminated. The container should preferably have the shape of abottle and be ready to dispense a liquid in the upside-down position ina reliable way without the invention being, however, limited to thebottle shape and the liquid contents.

According to the invention the substantially dimensionally stable outercontainer is equipped on its bottom with a closed, at least partlywelded seam which covers the weld seam of the inner container, wherebythe bottom of the outer container is closed and the weld seam of theinner container is held or permanently clamped in the bottom area of theouter container which is closed in this way. Furthermore, on itsshoulder section the outer container has at least one unwelded seamdefined by opposite wall sections of the outer container which are notbonded or welded to each other whereas the inner bag is tightly closedin this area by weld seams so that air can here enter into the spacebetween the outer container and the inner container. Two unwelded orunbonded seams are preferably provided over part of the two shouldersections of the container.

The unwelded seams on the shoulder section of the outer container can beformed by giving the two-layered tubular preform, from which thecontainer of the invention is blown, a diameter which is greater thanthat of the container opening or optionally greater than the neck of thecontainer, so that, when the blow mold is closed, the tubular preform issqueezed off in the shoulder area for removing excess material. In thesqueeze area of the shoulder section material of the inner bag is thenpositioned between the material of the outer container which is therebyspaced apart, so that said material cannot be welded or bonded toitself.

The closed, at least partly welded seam on the bottom of the outercontainer is formed by the special shape of the squeeze area of the blowmold at the bottom side. The excess material is here squeezed off thematerial of the outer container is displaced at both sides of the seamand untied to obtain an outwardly oriented web. These two operations ofsqueezing off and uniting material of the outer container at both sidescan be carried out simultaneously when the mold is being closed, or theymay be performed in separate successive steps by uniting the material ofthe outer container which is still in its plastic state in a separatestep and after the blow molding of the container of the invention toform a closed weld seam covering the squeeze seam.

The bottom of the container of the invention is preferably made concavein such a way that the weld seam projecting from the offset bottomsurface does not protrude beyond the annular outer region of the bottom,so that the stability of the container is not impaired by the eitherpartly or fully welded seam which is at any rate closed.

The seam of the inner bag is claimed in the bottom section of the outercontainer in such a way that the inner bag is held in the axialdirection of the bottle-shaped container. As a consequence, thearrangement of a riser becomes superfluous because the inner bag whichis kept in a stretched state can be emptied entirely without the aid ofsaid element, so that the costs of the inventive container are reduced.Of at least equal importance is the fact that the container of theinvention also operates in the upside-down position in a perfect way andcan be emptied entirely.

Foreign matter cannot penetrate into the closed bottom portion of thecontainer, nor can sharp-pointed articles be introduced to damage theinner bag wantonly, which has been easily possible with the knowncontainer.

The closed bottom seam of the outer container which permits an axialmounting of the inner bag without a riser is also of great importance tothe manufacturing method for the container of the invention if holes areto be formed in the walls of the outer container in the upper regionthereof for the purpose of a permanent pressure compensation betweeninner bag and outer bag. This shall be described in more detail furtherbelow.

As already mentioned, the open seam or seams permit the passage of airin the outer of the shoulder section of the outer container. If theseunwelded seams are large enough, a permanent pressure compensation canbe accomplished by said seams between inner bag and outer bag, so thatno other measures are required.

This, however, is normally not the case because the unconnected oppositeborder edges of the outer container tend to rest on each other in thepresence of a negative pressure in the area of the open seam. It istherefore suggested in an advantageous embodiment of the invention thatat least one hold, preferably a plurality of holes, should be formed inthe wall of the outer container for permitting a permanent pressurecompensation. These holes should be provided in an especiallyadvantageous way in the upper portion of the outer container, i.e. inthe shoulder area or in the upper section of the preferably cylindricalouter wall of the outer container because these holes can be concealedaccording to the invention in the way described further below.

According to the invention the holes are made after the blowingoperation in that a negative pressure is exerted on the inner bag sothat the latter contracts. Since the inner bag is fixed to the bottom ofthe outer bag, it collapses radially upon exertion of said negativepressure and detaches over its entire length from the wall of the outercontainer. If the inner bag was not held on the bottom, it would liftfrom the bottom portion and contract upwards in the direction of thecontainer neck, remaining in the upper cylindrical wall portion and inthe area of the shoulder section in contact with the wall of the outercontainer. In this latter case it would be impossible to form holes inthe upper region of the outer container because the inner bag would bedamaged thereby.

By contrast, the inner bag becomes fully detached from the wall of theouter container in the manufacturing method of the invention as alreadystated (except for the lower fixing seam and preferably the neckportion).

The negative pressure can be exerted on the inner bag in that a mandrelis positively inserted (optionally with an annular seal) into thecontainer neck and communicates with a vacuum pump via a suction line.Pressure compensation is preferably effected through the unweldedshoulder seams. The invention is, however, not limited thereto. Rather,the arrangement of the container neck between the outer container andthe inner container.

The holes can be formed in the wall of the outer container by allsuitable methods, e.g. by ultrasound or mechanically through perforationby means of needle-shaped pins.

The entry of air through the shoulder seams can be promoted during thestep of forming the holes by compressing the container laterally in sucha way that the opposite border edges of the outer container areadditionally spaced apart from each other in the area of the shoulderseams. This should preferably be done in a state in which the outercontainer is no longer plastically deformable, so that the containerassumes its original shape again.

In contrast to the bottom portion of the container, all openings in thewall of the outer container in the shoulder portion and the upper wallportion are to be concealed. To this end, this portion should be coveredexternally with the housing of the pump to be mounted on the containeropening. For this purpose it is suggested that the housing of thenormally used pumps should be extended such that it surrounds the wholeshoulder portion and optionally part of the preferably cylindrical outerwall of the outer container. The openings are consequently not exposedto the outside, so that the space between the outer casing and the innerbag is not soiled and the intactness of the bag is ensured despiteexternal action (if the outer housing is not damaged). Moreover, thewrong impression that the container is damaged can no longer be created.

The unwelded shoulder seams should preferably extend only over part ofthe shoulder section up to the container opening, which is the casewhenever the diameter of the tubular preform is smaller than thediameter of the preferably cylindrical container wall. The remainingclosed outer ring of the shoulder section increases the strength of thecontainer.

As stated, the container of the invention is preferably shaped in theform of a bottle, the shoulder section passing into a container neck sothat the unwelded seams of the shoulder portion are continued in theneck portion up to the opening thereof. In this context it isadvantageously suggested that an outwardly oriented ring onto which thepump can be snapped with an associated circumferential wall should bemolded onto the edge of the container neck on the opening thereof. Theoutwardly oriented snap-on rim of the container neck is sealed or weldedduring its formation by a mandrel, which is inserted into the blow mold,by displacing material of the outer container in the area of the squeezeseam so that the snap-on ring is firmly closed on all sides. The permitsa tight connection of the pump which is mounted on the snap-on ring andengages the interior of the inner bag. In addition, the snap-on ring isradially acted upon inwardly by a circumferential wall of the pump whichsurrounds said ring and is snapped thereunto, so that the snap-on ringwould even be retained if its welding was incomplete along the squeezeedge. The special design of the edge of the container neck ensures thatthe pump can be mounted on the container opening tightly and firmly sothat a perfect operation is ensured.

The invention is, however, not limited to this embodiment, but a boltedconnection may e.g. be provided on the container neck.

The inner surface of the neck should advantageously widen slightlyupwards and conically, this conical seat of the pump contributing to theeffect that the inner bag is retained in the neck portion. Moreover,material is mixed by sizing the neck portion, so that outer containerand inner bag are held together in the neck portion.

PP is preferably suggested as the material of the outer container whilethe inner bag expediently consists of polyethylene. Of course, theinvention is not limited to the use of these materials. Rather, otherthermoplastic materials that do not combine with each other duringcoextrusion and the subsequent blowing operation are also suited.

The use of polypropylene with an additive, preferably a release agentwhich facilitates the release from the polyethylene layer, as is alsosuggested according to the invention, makes the recycling of thecontainer easier.

When viewed in cross-section, the weld seam of the outer container inthe squeeze area of the bottom has preferably a kite-like shape and isin alignment with the weld seam of the inner bag which is firmly clampedby the additional wall section of the outer container.

The container of the invention avoids the above-mentioned disadvantagesof the known container without requiring any expensive means therefor.The openings in the shoulder portion and optionally holes in theshoulder portion or the upper portion of the wall of the outer containercan be concealed by a pumping housing section covering said portion.This measure is comparably with the insertion of a riser, so that themanufacture of the container of the invention does virtually not lead toany additional costs. Furthermore, the container of the inventionreliably discharges it contents in the upside-down position as well.

THE DRAWINGS

Other details of the invention become apparent from the followingdescription taken in conjunction with the drawing, in which:

FIG. 1 is a partial sectional side view of a container of the inventionwith an installed pump and an inner bag which is already emptied inpart;

FIG. 2 is a longitudinal section through the container of FIG. 1;

FIG. 3 is a perspective view of the container;

FIGS. 4a-4c illustrate successive steps in the making of the containerby coextrusion blow molding;

FIG. 5 is a cross-section through the squeeze area in the shoulderportion;

FIG. 6 is a cross-section through the area of the snap-on ring; and

FIG. 7 is a cross-section through the area of the bottom weld seams ofthe inner bag and the outer bag.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is first of all made to FIGS. 4a-4c which show successivesteps of making a bottle-shaped container according to the invention. Atubular preform 1 which consists of two concentric material layers exitsfrom an extrusion head 2 and is arranged between the opened halves of ablow mold 3 which is closed when preform 1 has reached the lengthrequired for making a bottle-shaped container. Preform 1 consists of anouter material layer 4 for forming a dimensionally stable outercontainer 5 and of an inner material layer 6 which is blown up to forman easily deformable inner bag 7. The two material layers 4 and 5consist of different thermoplastic materials which cannot be welded orbonded to each other.

As becomes apparent from the illustration of FIGS. 4b, which is rned by90° in comparison with FIGS. 4a and 4c, preform 1 has a diameter whichis greater than the outer diameter of a neck 8 of the bottle-shapedcontainer and which is smaller than the outer diameter of thecylindrical outer wall 9 of the container.

As a result, excess material is squeezed off in both the area ofshoulders 10 and neck 8 and the bottom area when the two halves of themolds are closed.

While in the area of shoulder 10 and neck 8 the material of the innerlayer 6 is positioned between the material of the outer layer 4 alongthe squeeze edge, which prevents the outer material layer 4 from beingwelded or bonded to itself, an outwardly projecting weld seam 11 ispreferably formed in the bottom area due to the special shape of theblow mold. Said weld seam consists at least in part, i.e. in the rangeof a few tenths of a millimeter, of the outer material layer 4, wherebythe outer container 5 is closed in the area of the squeeze edge at thebottom side. A complete weld seam 11, i.e. one which is closed over itstotal height, can also be formed by displacing material of the bottomlayer which is still in its plastic state in a step following the blowmolding step.

By contrast, the inner bag 7 is welded in both squeeze areas, i.e. atthe bottom and in the shoulder and neck area because, when the moldhalves are closed, the material of the inner layer 6 is pressed againstitself without another material being inserted, so that tight weld seams12 and 13 are formed in the squeeze areas.

The unwelded seams 14 which have been formed in the shoulder and neckarea of the outer container 5 permit the entry of air into space 15which is provided between the dimensionally stable outer container 5 andthe flexible inner bag 17.

As becomes especially apparent from FIGS. 2 and 7, the weld seam 12 ofthe inner bag 7 at the bottom side is fixed in the bag of the outercontainer 5, so that the inner bag 7 is held in axial direction whenbeing emptied, as outlined in FIG. 1.

After the two halves of blow mold 3 have been closed, a sizing mandrel16 is introduced into the mold cavity to finish neck 8 of the containerwith an outwardly oriented snap-on ring 17 and to squeeze off excessmaterial, the preform being additionally blown up to obtain the finishedcontainer. The sizing operation effects a certain mixing of the materialof the outer layer 4 and of the material of the inner layer 6, so thatthe inner bag 7 is held in the neck area on the outer container 5. Thisis also supported by an outwardly oriented small thickened rim portion18 on the upper edge of the inner bag 7. This thickened portion restsinwardly on the snap-on ring 17. In the area of the squeeze seams thesnap-on ring 17 is sealed or welded through the deformation caused bythe sizing mandrel 16 because outer layer material comes into contactwith itself in these areas due to the material movement.

As shown in FIG. 1, a pump 19 engages the container opening 20 and gripsthe snap-on ring 17 from behind with an annular attachment on acylindrical wall 21. As a result, the snap-on ring 17 is firmly heldtogether even if it is only incompletely sealed or welded in the are ofthe squeeze seams. Furthermore, pump 19 includes a cylindrical outerwall 22 which entirely covers the openings of the outer container 5 andextends almost down to the bottom area of the container. An outwardlyoriented holding section 23 is molded onto the lower end of thecircumferential wall 22 for operating pump 19.

FIG. 5 is an enlarged view of a squeeze seam in the area of should 10and neck 8 of the container. Excess material 24 is squeezed off bysqueeze edges 25 of the two mold halves 3, a tight weld seam of theinner bag 7 forming within mold 3 because the material layer 6 thereofrests on itself whereas material layer 4 is spaced apart by theinterposed weld seam of material layer 6 and is not welded to itself.This creates an air entry opening 14 in the outer container 5.

FIG. 7 is an enlarged view of the bottom weld seam 11 of the outercontainer 5 which can be formed due to the special shape of the blowmolding halves. When viewed in cross-section, weld seam 11 is anapproximately kite-shaped lower extension of material layer 4, whereby athickened portion if formed in which the interior weld seam 12 of theinner layer 6 is firmly embedded or clamped. In the bottom weld seam 11material of the outer layer which is united from both sides of the seamrests on itself at least over part of the seam height, resulting in anadequate welding for closing the bottom and for holding the inner bag inaxial direction. As for a preferred embodiment of the weld seam 11,reference is made to the dimensions shown in FIG. 7.

FIG. 6 is an enlarged view of details of the shape of snap-on ring 17 onthe upper edge of the slightly conically broadening neck 8 of thecontainer of the invention.

FIG. 3 shows holes 27 in the radially outer annular portion of theshoulder section of the outer container 5.

With respect to FIGS. 1 and 2 it should be noted that the central bottomportion of the container is concavely set back inwards to such an extentthat the projecting bottom weld seam 11 terminates in the plane 26 ofthe stand surface of the container, so that the stability of thecontainer is not impaired.

We claim:
 1. A container made in a coextrusion blow molding process andhaving a substantially dimensionally stable outer container having abottom and an upper shoulder neck, and opening, and an easily deformableinner bag within the outer container, and said outer container and innerbag being composed of different thermoplastic materials, the improvementcomprising a weld seam on the bottom of the inner bag and a weld seam onthe bottom of the outer container, the weld seam of the inner bag beingclamped by the weld seam of the outer container and being held thereby,and said upper shoulder of said outer container comprising an unweldedopen seam formed between two opposite wall sections of said uppershoulder.
 2. The container of claim 1, wherein a pair of unwelded openseams are provided in said upper shoulder.
 3. The container of claim 1,wherein the weld seam on the bottom of the outer container comprises anoutwardly projecting web.
 4. The container of claim 1, wherein a hole isformed in the outer container.
 5. The container of claim 4, wherein saidhole is formed in an upper portion of the outer container.
 6. Thecontainer of claim 1, additionally comprising a ring molded around theouter container opening.
 7. The container of claim 1, wherein thecontainer is formed by blow molding of a coextruded tubular preformhaving a diameter greater than the finished neck of the container. 8.The container of claim 1, wherein the outer container is composed ofpolypropylene and the inner bag is composed of polyethylene.
 9. Thecontainer of claim 1, wherein said outer container is engaged by thehousing of a pump, said unwelded open seam being covered by saidhousing.